[SUGGESTION] New config option similar to `unwrapResponseData` that preserves error types

[Roman-Octavian]

Suggestion:

Would it be desirable to have another option unwrapResponseDataWithErrors or perhaps to turn unwrapResponseData into a union 'disabled' | 'responseOnly' | 'responseAndError'?

At the moment, it seems that unwrapResponseData is not including the error and default response types.

Here:

swagger-typescript-api/templates/base/http-clients/fetch-http-client.ejs

Lines 170 to 175 in 0e251bb

	...params
	<% if (config.unwrapResponseData) { %>
	}: FullRequestParams): Promise<T> => {
	<% } else { %>
	}: FullRequestParams): Promise<HttpResponse<T, E>> => {
	<% } %>

This could be something like this instead:

<% if (config.unwrapResponseData) { %>
    }: FullRequestParams): Promise<T> => {
<% } else if (config.unwrapResponseDataWithErrors) { %>
    }: FullRequestParams): Promise<T | E> => {
<% } else { %>
    }: FullRequestParams): Promise<HttpResponse<T, E>> => {
<% } %>

Maybe I am misunderstanding the intent behind unwrapResponseData and this is not a good idea for reasons. But if this is something that could be useful, I am happy to contribute with a PR.

Context

I have the following (shortened) OpenAPI spec:

openapi-spec.json

The takeaway from this specification is that I expect the return type to be something like this:

export type ApiResponse =
  | {
      success: 'true';
      data: object;
    }
  | {
      success: 'false';
      error:
        | 'bad-request'
        | 'github-api-error'
        | 'parse-or-unknown'
        | 'missing-envs'
        | 'blob-storage-error'
        | 'file-too-large';
      description: string;
    };

I generate a client from the specification above using swagger-typescript-api version 13.1.3:

import { generateApi } from 'swagger-typescript-api';
import specification from '...';

(async () => {
  await generateApi({ spec: specification, output: process.cwd(), unwrapResponseData: true });
})();

The problem

The client works, but unwrapResponseData only includes the response type for status 200, so the return type that I'm actually getting is this:

export type ApiResponse = {
  success: 'true';
  data: object;
};

The solution

If I want the return type to include the error; in the generated client, all I need to do is modify this line:

swagger-typescript-api/templates/base/http-clients/fetch-http-client.ejs

Line 172 in 0e251bb

}: FullRequestParams): Promise<T> => {

To be

  public request = async <T = any, E = any>({
    body,
    secure,
    path,
    type,
    query,
    format,
    baseUrl,
    cancelToken,
    ...params
  }: FullRequestParams): Promise<T | E> => { // Added | E here

Instead of

  public request = async <T = any, E = any>({
    body,
    secure,
    path,
    type,
    query,
    format,
    baseUrl,
    cancelToken,
    ...params
  }: FullRequestParams): Promise<T> => {

And then my types are assigned as expected: